Contact

Bret M. Webb, Ph.D., P.E., D.CE
Professor
University of South Alabama
150 Jaguar Drive, SH3142
Mobile, AL 36688 USA
Phone: (251) 460-6174
Fax: (251) 461-1400
Email: bwebb@southalabama.edu

Research Positions

None available at this time

Current Research Assistants

SE Students
Garland Pennison

 

MSCE Students
Patrick Hautau
Marshall Hayden
Kate Haynes
Justin Lowlavar
Vijaya Satya Lohitha Mukkamala
Jackie Wittmann

 

Undergraduate Students
Derek Kelly
Rh'Monte Wilson

Former Students

MSCE Students
Bryan Groza (2016)
Kari Servold (2015)
Chris Marr (2013)
Richard Allen (2013)
Miyuki Matthews (2012)

 

Post Docs
Jon Risinger
Jungwoo Lee

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I use SonTek’s HydroSurveyor (HS) software on our Jag Ski when collecting bathymetric data. I prefer to use this instead of their RiverSurveyor Live software because of its line planning, navigation, and absolute RTK capabilities. One of the nice things about HS–when it was released–was its ability to reference aerial imagery via online map tile servers. However, this capability disappeared in early 2017 when the MapQuest tile server ceased to exist.

Not wanting to lose the ability to plan surveys with current aerial imagery in the background, I decided to figure out how to import imagery. While this capability of HS has always existed, and while it is documented in the user manual, I never had the patience to figure it out. Until I had to! Here is a step-by-step process that I followed to make this work. Note that I will reference the GIS software “QGIS” in my steps. This stands for Quantum GIS (click here). Any GIS software could be used as a substitute, but I prefer to use QGIS because it works across all computing platforms and I commonly have to swap back and forth between a Mac and a PC.

 

  1. Download NAIP imagery from USGS National Map Viewer (click here)
  2. The image will be a JPEG2000 (jp2). Images after 2013 are projected in WGS 1984 Web Mercator Auxiliary Sphere projection (EPSG 3857), which is exactly what you need for the HS software.
  3. Open your image in QGIS, define the CRS as EPSG 3857 (WGS84 Mercator)
  4. Save your file with a new name as a rendered GTIFF using the same CRS (EPSG 3857)
  5. In QGIS, go to Raster / Projections / Extract Projection. Select your file created above (tiff) and then process.
  6. Rename the world file with extension “tfw” instead of “wld”. (Note that the remaining steps will not work unless you complete this one. The HS software requires a world file, but you don’t get one when you download the imagery from the USGS National Map Viewer.)
  7. Open HydroSurveyor, select Tasks / Import Georeferenced Image, and then select your tiff file(s).
  8. Select WGS-84 Mercator in the following window.
  9. Save the tiled data with a new name.
  10. In HydroSurveyor, click “Add Layer” and then “Browse for File” … select your tile files.
  11. Note that you may need to expand your image layer using “>>” and then select “zoom to layer” in order to see your imagery.

 

Do you have to use imagery from the USGS National Map Viewer? No, not at all. Any georeferenced aerial imagery will work so long as you can 1) reproject it to WGS84 Mercator (EPSG 3857) and 2) extract/create/obtain the image world file. That said, another good option for imagery is TerraServer, but those images can be expensive.

 

Dog RIver Park

Dog River Park: Mobile, AL

Some of the usual suspects in Alabama and Mississippi have been busy developing technical guidance on living shorelines. What’s different about these new documents is that they are aimed at property owners and contractors instead of practitioners, scientists, engineers, etc. Our goal, as a community of living shorelines practitioners, has been to push some of our knowledge down to these underserved groups in hopes that they might make use of our regional general permits for living shorelines in Alabama and Mississippi.

Well after a couple of years of hard work (and some delays), I’m happy to say that they are finally available. Please click on the links below to download the PDFs. These projects involved too many friends and agencies to list here in this post, so please be sure to review the acknowledgments in each document. However, I would like to express our collective gratitude to the primary funding agencies (NOAA and GOMA) as well as the Mobile Bay National Estuary Program and the Southern Environmental Law Center for their support and hard work.

 

Living Shorelines: A Guide for Alabama Property Owners

 

Living Shorelines: A Technical Guide for Contractors in Alabama and Mississippi.

 

{Edit: Fixed a problem with the links. The documents should load in the same browser window/tab now without trying to open a new one. Apologies for the troubles.}

boatwakestudysite-westfowlriverWe recently deployed a GoPro Hero 3 camera and two RBR D|wave gages to study boat wakes and boat traffic at a site on West Fowl River (AL) over the Labor Day weekend. The GoPro is set to capture photos every 10 s using the time lapse mode. It is wired to an external battery using the LongShot battery elimination system. The wave gages were configured independently such that one is sampling continuously and the other is processing bursts of waves every five minutes. These two sampling schemes will allow us to study the boat wake signatures in great detail (continuous sampling) and also in summary form (wave bursts). The camera system should allow us to match boat wake signatures with the vessels that generated them. While not perfect, we may also be able to estimate boat size and speed from the time lapse photos.

Here is a time lapse video (~30 seconds) of the installation at our study site…

 

 

Pres-cover-pageThe latest study out of our ACES center (Applied Coastal Engineering & Science) is now available. The study, entitled “Lake Forest Mapping: Analysis of Shoaling and Pool Volumes,” was recently completed for the Lake Forest Property Owner’s Association and the City of Daphne with contracting support provided by the Mobile Bay National Estuary Program. The goals of the study were to determine how much sediment has accumulated in the Lake Forest lake (reservoir) since the time of dam construction in 1973/1974, where the largest accumulations of sediment have occurred, and what the remaining normal pool volume is within the lake.

We collected over 12,000 new elevation measurements within and around the lake to map the sediment elevations and also analyzed eight (8) shallow sediment push cores from the lake bed. The results of the study show that over 300,000 cubic yards of medium to coarse grained sediments have accumulated, or shoaled, within the present-day lake shoreline since 1973/1974. Approximately 80% of the lake has shoaled by some measurable amount since the time of dam construction, with some areas accumulating over ten (10) feet of sediment! As a result, the pool volume of the lake has decreased by about 60% due to the accumulation of sediments. The remaining volume could perhaps accommodate another 90 years of sediment input at the current reported rate of 7800 tons per year (as per Cook & Moss, 2008[1]), but the margin for error is quite large.

I presented these study results at a recent Mobile Bay National Estuary Program’s Project Implementation Committee Meeting. A copy of that presentation [2] can be downloaded {here}.  A copy of the final study report [3] can be downloaded {here}.  Please include proper attribution and/or citation [2,3] when reusing these data, results, graphics, and/or figures.

[1] Cook, M., and Moss, N. 2008. Analysis of Water Quality, Sediment Loading Rates, Biological Resources, and Impacts of Land-Use Change on the D’Olive and Tiawasee Creek Watersheds, Baldwin County, Alabama, 2008. Geological Survey of Alabama, Open File Report 08-11: 92 pp.

[2] Webb, B.M. 2016. Lake Forest Mapping: Analysis of Shoaling and Pool Volumes. Mobile Bay National Estuary Program Project Implementation Committee Meeting. August 18, 2016. Presentation.

[3] Webb, B.M. 2016. Lake Forest Mapping: Analysis of Shoaling and Pool Volumes. University of South Alabama, Center for Applied Coastal Engineering and Science, Technical Report No. 16-002F. 41 pp.

 

Fig07 for web site

Our manuscript entitled “Spatial Variability of Hydrodynamic Timescales in a Broad and Shallow Estuary: Mobile Bay, Alabama” has been published by the Journal of Coastal Research. The manuscript is currently available online as a pre-print. The final version with color will be available in the coming months. Please {click on this link} for access to the manuscript.

The results presented in this new manuscript by Webb and Marr (2016) were initially developed as part of Chris Marr’s thesis research back in 2013. This new manuscript presents a much more narrow focus of his work and some new analyses as well. For more information about this work please review the {thesis} by Marr and/or this previous {blog post}.